\begin{deluxetable}{llrl}
%\tabletypesize{\scriptsize}
%\rotate
\tablecaption{Log of observations\label{tab:obslog}}
\tablewidth{0pt}
\tablehead{\colhead{Facility} & \colhead{Id} & \colhead{exposure} & \colhead{date}}

\startdata
\toprule
Chandra & \dataset[ADS/Sa.CXO#obs/06438]{ObsId 6438} & 23 ks & 2006-12-10\\
\midrule
Spitzer & AOR 3656448  & 41.6 s & 2004-06-09\\
\midrule
FLWO    & filter: $B$ & 600 s & 2009-11-18\\
\bottomrule
\enddata

\end{deluxetable}